Peritransplant Energy Changes and Their Correlation to Outcome After Human Liver Transplantation

Abstract

Background: The ongoing shortage of donor livers for transplantation and the increased use of marginal livers necessitate the development of accurate pretransplant tests of viability. Considering the importance energy status during transplantation, we aimed to correlate peritransplant energy cofactors to posttransplant outcome and subsequently model this in an ex vivo setting.

Methods: Sequential biopsies were taken from 19 donor livers postpreservation, as well as 30 minutes after portal venous reperfusion and hepatic arterial reperfusion and analyzed by liquid chromatography-mass spectrometry for energetic cofactors (adenosine triphosphate [ATP]/adenosine diphosphate [ADP]/adenosine monophosphate [AMP], nicotinamide adenine dinucleotide /NAD, nicotinamide adenine dinucleotide phosphate / nicotinamide adenine dinucleotide phosphate , flavin adenine dinucleotide , glutathione disulfide/glutathione). Energy status was correlated to posttransplant outcome. In addition, 4 discarded human donation after circulatory death livers were subjected to ex vivo reperfusion, modeling reperfusion injury and were similarly analyzed for energetic cofactors.

Results: A rapid shift toward higher energy adenine nucleotides was observed following clinical reperfusion, with a 2.45-, 3.17- and 2.12-fold increase in ATP:ADP, ATP:AMP and energy charge after portal venous reperfusion, respectively. Seven of the 19 grafts developed early allograft dysfunction. Correlation with peritransplant cofactors revealed a significant difference in EC between early allograft dysfunction and normal functioning grafts (0.09 vs 0.31, P < 0.05). In the simulated reperfusion model, a similar trend in adenine nucleotide changes was observed.

Conclusions: A preserved energy status appears critical in the peritransplant period. Levels of adenine nucleotides change rapidly after reperfusion and ratios of ATP/ADP/AMP after reperfusion are significantly correlated to graft function. Using these markers as a viability test in combination with ex vivo reperfusion may provide a useful predictor of outcome that incorporates donor, preservation, and reperfusion factors.

Fig. 1. Cofactor changes during clinical reperfusion

ATP:ADP (A), ATP:AMP (B), Energy charge (C), NADH:NAD⁺ (D), FAD (E), GSSG:GSH (F) and NADPH:NADP (G) ratios before and after clinical reperfusion of the human liver. OOI, out of ice; PVR; portal vein reperfusion; HAR, hepatic artery reperfusion.

Fig. 2. Peritransplant energy charge changes

Difference in the dynamics of energy charge during clinical reperfusion of the human liver in normally functioning (NF) livers and early allograft dysfunction (EAD) livers. OOI, out of ice; PVR; portal vein reperfusion; HAR, hepatic artery reperfusion. Thick, uninterrupted lines present the mean for the 2 groups, while the interrupted lines present individual grafts.

Fig. 3. Cofactor changes during simulated reperfusion

ATP:ADP (A), ATP:AMP (B), Energy charge (C), NADH:NAD⁺ (D) ratio changes during simulated ex vivo reperfusion of the human liver. EC, energy charge.

Fig. 4. Simulated ex vivo reperfusion

Human liver at various stages of simulated ex vivo reperfusion (representative images), showing portal vein, hepatic artery and bile duct cannulation (A). ALT levels, pH (B) and lactate levels (C) during during reperfusion. Error bars depict s.e.m.

Fig. 5. Inflammatory injury markers during simulated ex vivo reperfusion

Levels of c-reactive protein (A) and TNF-α, IL-1β, and IL-12 during reperfusion. Error bars depict s.e.m.